Piston ring



Jan. 8, 1929. I

1,698,546 L. L. HOFFMAN PISTON RING Filed Jan. 30, 1926' Z F 3 a a m vm f Jgra% 65%; Mg z Patented Jan. 8, 192.9.

UNITED." STATES LORAN LEE HOFFMAN, OF MILWAUKEE, WISCONSIN.

- PISTON RING.

Application filed January 30. 1926. Serial No. 85,065,

tain a tight joint at alltimes with the cylinder, to provide means for urging the composite ring outwardly into contact with the cylinder walls, and/to so organize the piston that even in the'eventof failure of certain parts of the composite ring that the action of the compressed gases will be such as to hold the ring in contact with the cylinder.

An embodiment of theinvention is shown in the accompanying drawings, in which Figure 1 is a sectional view showing the piston and the rings and a portion of the cylinder.

Figure'2 is an enlarged fragmentary detail of a portion of the" iston. I

Figure 3 is a sectiona view on the line 3-3 of Figure 1 showing the outer piston rin F igure 4-is a" sectional, view on the line 44 of Figure 1 showing the inner piston rin 'l he piston 1 is turned to a slightly smaller diameter than the internal diameter of the cylinder-,2 in accordance with the usual practice. It is provided with a plu-' rality of annular rectan ar grooves 4 within which the composlte rings fit. series of small ducts 5 lead from the rectangular channels 4 to the'outer face of the piston, as clearly shown in Figures 1 and The composite ring comprises an outer 1 ring composed of a lurality ofaccurately 4 rings are out along different lines so that turned members 6. hese members are providedwith contacting beveled surfaces 7, as shown in Figure 3. The inner portion of the ring comprises a plurality of members 8 which contact with each other along radial faces 9, as may be seen from Figure 4.

It is to be noted from a comparison of Figures 3 and 4 that the inner and outer portions of the rings are formed of a different number of segments. five segments are shown in Figure 3 for the outer ring, and six segments in Figure 4 for the inner ring.

Further than this the faces 7 and 9 of the contacting portions of the outer and inner leaking is minimized. The adjacent faces For instance of the outer and inner rings are beveled, as

shown at 10 in Figure 2, and they, together with the outer andinner portions, form .in effect a wedge structure. The innerportion 8 of the ring is provided with an annular groove-upon its inner side within which is seated a split circular spring 12 (see Figure 2). This spring tends to open outwardly and thus forces the inner portion 8 against the outer portion 6 pressing such outer portion "against the cylinder and also wedging the portions 6 and 8 against the lateral sides of the rectangular slot 4 thus maintaining a gas tight joint. It is to be noted from Figure 2 that the upper edge of the member 6 is cut ofi as indicated at 13. This prevents the cutting of this edge into the cylinder with the consequent marring of such cylinder. i

i If for any reason the spring 12 should break, pressure is communicated to the members 8 and 6 through the duct 5 and consequently such members are forced outwardly into contact with the c linder. These rings are primarily intended for relatively'large cylinders such as the large cylinders employed in steam engines, but, obviously, the rings may be used for internal combustion an other ty es of engines. In the case of small cylin ers, it may be found suflicient to provide a single split in the inner and- A outer members in place of forming such members of a multitude of parts.

It will thus be seen that a composite piston rin has been provided which is so construct that it will at all times maintain a yielding firm joint with the cylinder and will also maintain a firm joint with the lateral walls of the rectangular grooves.

Although one form of the invention has been described in considerable detail, it is to be understood that the invention may be variously embodied and is, therefore, to be limited only as claimed.

I claim: a

1. The combination of a piston and a cylinder, such piston having a rectan ular peripheral groove and ducts leading t ereinto, a composite piston ring comprising an outer member composed of a plurality of parts, an inner member composed of a different number of parts, said inner and outer members having contacting beveled surfaces and resilient means ositioned interiorly 0 said inner member a or causing thering to expand and force the inner and outer members into contact with the lateral faces ofsaid roove.

2. he combination of a piston and a cylinder, said piston having a pair of grooves in its peripheral portion, said piston havinga duct leading from each groove through the adjacent face of the piston, a pair of piston rings located in each roove and having bevelled contacting sur aces, said rings contacting ndirectly with the side walls of the grooves, one of said rings of each pair constituting a packing ring and the other of said rings of each pair constituting an adjusting ring, said adjusting ring having an outer cut-away corner out of contact with rical surface provided with a groove, I

ing formedof a luralitygof portions with contacting faces or one ring arranged at a a different angle to a radial line from the contacting faces for the other ring, whereby "registering of the splits in the individual rings of a pair cannot occur. 7

In testimony that I clairn the foregoing I have hereunto 'set my hand at Milwaukee,

in the county of Milwaukee and State of Wisconsin. I g I I I I LORAN LEETHOFFMAN. 

